Ignition plug

ABSTRACT

An ignition plug for use in an internal combustion engine. An insulator which is attached to a plug body carries a center electrode and is formed beyond the latter with a pair of bores which extend transversely with respect to the center electrode and which carry a substantially C-shaped wire one leg of which extends across and is spaced from a free end of the center electrode, with the legs of this wire being respectively situated in the bores of the insulator. A grounded electrode is provided with an elongated portion extending parallel to and spaced from an intermediate portion of the wire which interconnects the legs thereof, so that in addition to the spark which will form between the center electrode and one leg of the wire, an additional spark will be provided between the grounded electrode and the intermediate portion of the wire.

United States Patent Kubo Sept. 23, 1975 15 1 IGNITION PLUG 2,852,713 9/1958 Gendron 3 313/123 [76] Inventor: Tunesuke Kubo, No. 20, ldogaya Naka chm Minampku, Yokohama Primary Examiner-Alfred L. Br0dy Kanagawa, Japan Attorney, Agent, or Firm-Stemberg and Blake [22] F1led: Jan. 31, 1974 ABSTRACT Appl. No.: 438,190

An ignition plug for use in an internal combustion engine. An insulator which is attached to a plug body carries a center electrode and is formed beyond the latter with a pair of bores which extend transversely with respect to the center electrode and which carry a substantially C-shaped wire one leg of which extends across and is spaced from a free end of the center electrode, with the legs of this wire being respectively situated in the bores of the insulator. A grounded electrode is provided with an elongated portion extending parallel to and spaced from an intermediate portion of the wire which interconnects the legs thereof, so that in addition to the spark which will form between the center electrode and one leg of the wire, an additional spark will be provided between the grounded electrode and the intermediate portion of the wire.

9 Claims, 6 Drawing Figures US Patent Sept. 23,1975 Sheet 10f2 3,908,145

F/GB' US Patent Sept. 23,1975 Sheet 2 of2 3,908,145

IGNITION PLUG BACKGROUND OF THE INVENTION An ignition plug of the above kind has been shown and described in an invention of the Japanese Patent application No. 1972 I 13145 invented by the present inventors. Since the ignition energy is supplied in this case from a linear spark discharge produced between the edges of the electrodes having a somewhat large po tential gradient, the ignition energy of this plug has been rather low. Under this situation, when the plug is applied to a rotary engine with a lower compression ratie, for instance, the ignition plug of a larger output must be utilized to promote the combustion of the fuel mixture.

Hence, it is an object of the present invention to im prove the aforementioned invention is such manner that an increased ignition energy and satisfactory ignition and combustion performance may be obtained.

BRIEF SUMMARY OF THE INVENTION According to this invention, the problem referred to in the above can be solved by an ignition plug an ignition plug comprising a plug body, an insulator fitted to the plug body, a center electrode fitted to the insulator on the center line thereof, a C-shaped intermediate with rigidly fitted to the end part of the insulator, and a grounded electrode projectedly provided to said plug body, wherein a spark gap is provided between the one end of said intermediate wire and said center electrode and a further spark gap is provided between said grounded electrode and said intermediate wire, characterized in that said grounded electrode is mounted in a parallel relation to the base of said intermediate wire to produce said further spark gap. The ignition energy can thus be increased since the spark discharge occurs as a broad band between the grounded electrode and the intermediate wire. The present invention thus makes it possible to markedly elevate the combustion perfor mance and power output of the internal combustion engine and thus contribute to the prevention of atmospheric pollution caused by the engine emission gases.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front view showing an ignition plug of the present invention;

FIG. 2 is a side elevation of the same, part being broken away;

FIG. 3 is a front view showing another embodiment of the ignition plug of the present invention;

FIG. 4 is a side elevation of the same, part thereof being broken away;

FIG. 5 is a plan view of the same; and

FIG. 6 is a side elevation showing an ignition plug of the same type as the embodiment shown in FIGS. 3 5, part thereof being broken away and the grounded electrode being omitted.

DETAILED DESCRIPTION OF THE INVENTION The present invention will be hereinbelow described in detail with reference to the attached drawings which show several embodiments of ignition plugs in accor dance with the present invention.

An insulator I is inserted in and threadedly attached at 4 to a plug body A. The end part of the insulator l is projected further outwardly from the end part of the plug body A and is formed with an upper transverse a. +4- m. .I 1 Wm uni-MM" through-hole 5 and a lower transverse through-hole 6. A center electrode 2 is fitted to the insulator I in a registration with the center line of the insulator I so that the upper end part of the electrode 2 is situated in the inside space of the lower through-hole 6. An intermediate wire B ofa generally C-shape having long and short sides of the C-shape is fitted with its long side into said through-hole 5 so that the end part b of its short side is introduced into the through-hole 6 in a confronting relation to the upper end part of the center electrode 2. A grounded electrode 3 is rigidly fitted to the plug body A parallel to the base b of the intermediate wire B so as to provide a spark gap c" therebetween.

In the embodiment shown in FIGS. 3, 4 and 5, a metallic plate 3a made of heat resisting material is mounted so as to bestride said insulator l. The electrode 3 is used at the same time as a heat radiator and has its two sides cut out, namely the sides facing to the base 11' of the wire B and to the end of the long side thereof fitted into and secured to said through-hole 5. An electrode plate 317 is mounted as by welding to said metallic plate 3a in a parallel relation to the base b of the intermediate wire B, and another electrode plate 3c is also mounted to said metallic plate 30 in a parallel relation to the end part of the long side of the wire B bent at about right angles to the main portion of said long side in the direction of said through-hole 6. Both said electrode plates 3b and 3c are formed as heat resisting metallic plates of tungsten, nickel or the like and are used at the same time as heat radiating means. Accordingly, the ignition plug of the present embodiment has one more spark gap than in the ignition plug shown in FIGS. I and 2. The reference numerals 7, 8 and 9 in the drawings denote respectively a block, a double nut, and a terminal connected to the center electrode 2.

The ignition plug of the present invention mounted to an engine, not shown, operates as follows: Under the high voltage applied between the grounded electrode 3 and the terminal 9, spark discharges are individually created at the spark gap between the center electrode 2 and the end part b of the intermediate wire B, and at the spark gap 6' between the grounded electrode 3 and the base b of the intermediate wire B, thus causing the ignition and resulting explosion of the fuel mixture contained in a cylinder, not shown. Since the grounded electrode 3 is mounted parallel to the base b of the intermediate wire B, the electrical field is nearly uniformly distributed in the zone of the spark gap c. Thus, the spark discharge thereat assumes a shape of a band of some breadth. Therefore, in accordance with the ignition plug of the present invention, the ignition energy is by far stronger and more effective than that obtained by the conventional ignition plug, and thus the ignition and combustion of the fuel mixture occurs reliably and completely in a manner to prevent the atmospheric pollution caused by the engine emission gases. Furthermore, the ignition plug of the present invention assures a fully effective combustion performance with use of only one ignition plug even is rotary engine with a lower compression ratio. In addition, in the embodiment shown in FIGS. 3, 4, 5 and 6, since the grounded electrode 3 has the metallic plate 3a rigidly fixed to the plug body A to bestride the insulator and made of heat resisting material so as to be used additionally as heat radiating means, any overheating of the electrode plates 3b and 3( can be effectively prevented owing to the heat dissipation performance of the metallic plate 3a. Furthermore, since the additional spark gap is provided between the electrode plate 3c and the end part of the intermediate wire B, the ignition energy is stronger and more effective than that obtained in the first embodiment shown in FIG. 1 and H0. 2.

What is claimed is:

1. In an ignition plug, a plug body having a central axis, an insulator carried by said plug body, a center electrode extending along said axis and having a free end, said insulator extending outwardly beyond said free end of said center electrode and being formed with a pair of throughholes which extend transversely with respect to said axis with one of said through-holes being situated next to and receiving said free end of said center electrode while the other of said through-holes is situated at the side of said one through-hole opposite from said free end of said center electrode, an intermediate wire of generally C-shaped configuration having a pair of legs respectively situated in said through-holes and at one side of said through-holes an intermediate elongated portion extending parallel to said axis and interconnecting said legs, said leg which is in said one through-hole extending across but being spaced from said free end of said center electrode to define a first spark gap therewith, and a grounded electrode connected with said plug body and having a portion extending parallel to but spaced from said intermediate portion of said wire for defining a second spark gap therewith and for providing in said second spark gap a spark discharge having the shape of a band the breadth of which equals the distance between said grounded electrode and intermediate portion of said wire.

2. The combination of claim 1 and wherein said grounded electrode has a substantially straight configuration and is spaced from said insulator.

3. The combination of claim 2 and wherein said grounded electrode is situated at one side of said intermediate elongated portion of said wire.

4. The combination of claim 3 and wherein said leg of said wire which is in said one through-hole is shorter than the other leg of said wire, and said wire having at an end of said other leg distant from said intermediate portion of said wire an elongated free end portion ex tending from said other toward said one through-hole across a part of said insulator which is situated between said through-holes thereof.

5. The combination of claim 1 and wherein said insulator has a free end surface distant from said plug body and a pair of opposed side surfaces extending from said free end surface toward said plug body, said throughholes being situated between said side surfaces of said insulator, and said grounded electrode having a sub stantially U-shaped portion engaging said end and side surfaces of said insulator and said portion of said grounded electrode which extends parallel to said intermediate portion of said wire to define said second spark gap therewith being fixed to and extending from said U-shaped portion of said grounded electrode, said grounded electrode being made of a heat-resisting material and acting as a heat radiator.

6. The combination of claim 5 and wherein said portion of said grounded electrode which defines part of said second spark gap is fixed to and extends from a part of said grounded electrode which extends along one of said side surfaces of said insulator.

7. The combination of claim 5 and wherein said leg of said wire which is in said one through-hole is shorter than the other leg of said wire, said wire having at an end of said other leg thereof which is distant from said intermediate portion of said wire an elongated free end portion which extends parallel to said axis across a part of said insulator which separates said through-holes from each other, and said grounded electrode having a second portion which extends parallel to and is spaced from said elongated free end portion of said wire to define a third spark gap with said free end portion of said wire.

8. The combination of claim 7 and wherein said portions of said grounded electrode which respectively cooperate with said intermediate portion and free end portion of said wire to define said second and third spark gaps therewith, respectively, respectively extend from opposed parts of said grounded electrode which engage said side surfaces of said insulator.

9. The combination of claim 7 and wherein said intermediate elongated portion of said wire and said free end portion thereof are situated between said portions of said ground electrode which define said second and third spark gaps with said intermediate and free end portions of said wire. 

1. In an ignition plug, a plug body having a central axis, an insulator carried by said plug body, a center electrode extending along said axis and having a free end, said insulator extending outwardly beyond said free end of said center electrode and being formed with a pair of through-holes which extend transversely with respect to said axis with one of said through-holes being situated next to and receiving said free end of said center electrode while the other of said through-holes is situated at the side of said one through-hole opposite from said free end of said center electrode, an intermediate wire of generally C-shaped configuration having a pair of legs respectively situated in said through-holes and at one side of said through-holes an intermediate elongated portion extending parallel to said axis and interconnecting said legs, said leg which is in said one through-hole extending across but being spaced from said free end of said center electrode to define a first spark gap therewith, and a grounded electrode connected with said plug body and having a portion extending parallel to but spaced from said intermediate portion of said wire for defining a second spark gap therewith and for providing in said second spark gap a spark discharge having the shape of a band the breadth of which equals the distance between said grounded electrode and intermediate portion of said wire.
 2. The combination of claim 1 and wherein said grounded electrode has a substantially straight configuration and is spaced from said insulator.
 3. The combination of claim 2 and wherein said grounded electrode is situated at one side of said intermediate elongated portion of said wire.
 4. The combination of claim 3 and wherein said leg of said wire which is in said one through-hole is shorter than the other leg of said wire, and said wire having at an end of said other leg distant from said intermediate portion of said wire an elongated free end portion extending from said other toward said one through-hole across a part of said insulator which is situated between said through-holes thereof.
 5. The combination of claim 1 and wherein said insulator has a free end surface distant from said plug body and a pair of opposed side surfaces extending from said free end surface toward said plug body, said through-holes being situated between said side surfaces of said insulator, and said grounded electrode having a substantially U-shaped portion engaging said end and side surfaces of said insulator and said portion of said grounded electrode which extends parallel to said intermediate portion of said wire to define said second spark gap therewith being fixed to and extending from said U-shaped portion of said grounded electrode, said grounded electrode being made of a heat-resisting material and acting as a heat radiator.
 6. The combination of claim 5 and wherein said portion of said grounded electrode which defines part of said second spark gap is fixed to and extends from a part of said grounded electrode which extends along one of said side surfaces of said insulator.
 7. The combination of claim 5 and wherein said leg of said wire which is in said one through-hole is shorter than the other leg of said wire, said wire having at an end of said other leg thereof which is distant from said intermediate portion of said wirE an elongated free end portion which extends parallel to said axis across a part of said insulator which separates said through-holes from each other, and said grounded electrode having a second portion which extends parallel to and is spaced from said elongated free end portion of said wire to define a third spark gap with said free end portion of said wire.
 8. The combination of claim 7 and wherein said portions of said grounded electrode which respectively cooperate with said intermediate portion and free end portion of said wire to define said second and third spark gaps therewith, respectively, respectively extend from opposed parts of said grounded electrode which engage said side surfaces of said insulator.
 9. The combination of claim 7 and wherein said intermediate elongated portion of said wire and said free end portion thereof are situated between said portions of said ground electrode which define said second and third spark gaps with said intermediate and free end portions of said wire. 